During one of her deep-sea dives, Angela Ziltener, wildflife biologist from the University of Zurich, noticed Indo-Pacific bottlenosed dolphins (Tursiops aduncus) brushing their bodies against corals or sea sponges lining the seafloor. After more than a decade, she and her team may have figured out why the animals behave this way: they may use corals and sea sponges as their own private pharmacies.

The invertebrates, mainly gorgonian corals (Rumphella aggregata) and leather corals (Sarcophyton sp.), make antibacterial and antioxidant compounds that are probably released into the waters of the Northern Red Sea when dolphins make contact. Through rubbing against them, dolphins can maintain a healthy skin and treat active skin infections. Ziltener says the team has yet to see proof of a coral cure and whether dolphins prefer to rub specific body parts on specific corals in such an “underwater spa.”

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